I've come about this thread by accident and discovered what you attend to do on the Oric. This reminds me of what was done on the Thomson machines few years ago. Since the Thomsons and the Orics almost share the same gfx capabilities, I think you might be interrested by the compression/encoding technique as well as the way to to get read of error diffusion (bad for flickering and compression) or efficiently render colors while still keeping the same frame-rate.

A sample of what can be done on plain TO7 is available in this message (in French, but I think this doesn't matter to view the result) and can also be tested under Windows using self-contained/preconfigurted emulator available in the download link provided in that message. Actually the whole thread might be interresting to read as well since it started with a very low bandwidth & quality but both improved regularly other the time.

The full technical detail on "how is it working?" is explained there (still in French; sorry guys, you'll have to use google translate and search for the message starting with "Great question!".) Notice that the solution used to display color should ring a bell for some old Oric coder

It is also worth mentioning that in addition to the TO7, the poor Hector machine is also capable of playing a colored video (and later B&W with sound on a 1bit buzzer) so the Oric should definitely be able to get very very good results sooner or later since the current result is already quite good and doesn't use any of the tricks we devised to compress and achieve higher frame-rate or greater image quality.

A sample of what can be done on plain TO7 is available in this message (in French, but I think this doesn't matter to view the result) and can also be tested under Windows using self-contained/preconfigurted emulator available in the download link provided in that message. Actually the whole thread might be interresting to read as well since it started with a very low bandwidth & quality but both improved regularly other the time.

This video is a proof of concept. It was done only to show how fast the interface is. It can load at least 46 KB per second, I could wrote some faster routines, but i don't think that the result will be more impressive (if i keep this method).

Twilighte did a kind of video (a part of a demo in 2003 : never released), and i did also an example in 2003 (never released too) but in text mode (with all the charset modifyed on the fly).

For the video displayed above, each frame (6 KB in raw format) is loaded from sdcard to the hires screen. There is no cruncher. But this video shows the maximum bandwidth allowed with a mass storage : 6502 is the limit, it's not the storage (for example, on CPC, with the same chip at the same frequency, they can load 128 KB per second, but Z80 is also the limit, it's not the sdcard chip).

Of course, i could do better, there is a lot of way to have more frames. But this player is 10 lines of assembly (it calls FOPEN, FREAD Routines from OS). This video is only 30 minutes of my free time

Anyway, i have not enough to time to improve this video (as i usually said, i am doing this hardware, Emulation of this hardware, OS, primitives for this OS etc and others new stuffs .